My five years old Canon imagePROGRAF PRO-1000 had been sitting idle for a couple of months, and my Mac refused to start printing, even though everything seemed OK.
The printer displayed B208 as an error code, and asked me to contact Service Center. If I managed to turn the printer on and not have that code show up, it complained about a full maintenance cartridge (even though it was brand new).
My local photo store said there’s a way to bypass the full cartridge prompt (by some googling), but I never got around to that.
What worked for me was to shut down the printer, unplug all the ink cartridges, turn the printer back on and then insert the inks again. Apparently some contacts might get “clogged up”.
Here’s a video from someone who solved it the same way.
So, lesson learned - don’t let you printer sit for too long…
I also tried resetting the network, turning of WiFi, replacing the maintenance cartridge. Not sure which of these worked in the end but I assume reconnecting the ink tanks.